The interspinous intervertebral distractors are devices apt to space two adjacent vertebrae, and may be designed for permanent implantation in the space between the spinous processes of said vertebrae.
Typically, the interspinous devices have the purpose of keeping an intervertebral distraction so as to limit the loads transmitted between the vertebrae due to, for example, degenerative diseases of the intervertebral disk, and to contain the associated painful manifestations.
In addition, the interspinous distractors may be used for spinal arthrodesis (fusion), i.e., to inhibit relative movements between adjacent vertebrae, making the articulation static (i.e. fixed) instead of mobile.
Compared to other spinal implants, the interspinous distractors can be easily inserted in situ, thanks to the relative ease with which the spinous processes of two adjacent vertebrae allow little divarications.
To ensure a stable position between the vertebrae, the distractor is typically equipped with side flaps suitable to abut on the spinous processes.
US 2008/0108990 A1 describes an interspinous implant which comprises two side stops, each defined by four segments pivotally connected at respective ends. The implant also comprises a central spacer disposed between stops and an auction rod which passes through the spacer.
US 2010/0318127 A1 describes an interspinous implant comprising a central body, two lateral wings rotatable on a longitudinal axis of the central body and a rod connected to the wings by means of a threaded connection.
US 2014/0188170 A1 describes a system of fixing of a spinous process based on an expandable central body.
US 2013/0325067 A1 describes an interspinous device equipped with a central body and rotatable lateral distractors.
However, the known distractors have some drawbacks still unsolved.
In particular, the need to spread apart in situ the above-mentioned stabilizing flaps has so far resulted in mechanically complex systems and/or devices that are not very structurally resistant, making some distractors globally unreliable.
The complexity of systems so far proposed constitutes a significant restriction even for the purpose of miniaturization of the distractor, for example, for individuals of small stature or infant age.
A further problem is then represented by the tools necessary to perform the above mentioned spreading apart, often too complex and rather complicated to operate percutaneously, at the expense of the speed of the intervention.